Heater control question

[SkidPalace]

I wonder if anyone has experience with a sticky temperature controller (analog rotary) on a 2000 T4R SR5?
I noticed during a rare cold spell early in the summer that it had a hard time moving towards the hot range.
I just applied a bit of pressure and it eventually freed up.
I just went to crank on the heat last night and it was sticky again.
I applied a bit of pressure and it didn't budge. I applied a bit more pressure and heard a snap in the knob istelf.
So anyway, I looked under the dash and followed the cable to where it attaches to what another post referred to as the blend door (the white plastic linkages at the bottom of the heater unit). I uncoupled the cable from the mechanism. The knob and cable move perfectly without resistance. The linkage, however, is very difficult to move but it does move by hand.
Although the heat operates to some extent without the operation of this blend door, I would like it to operate properly.
Is this something that can be lubricated, or am I out of luck.
Since I forced the temp knob too much, I will have to get the blend door linkage to operate very smoothly or else the knob will likely continue to jump its gears.
Any suggestions?

 

[quicksilvr]

Massive 3 year bump.....because I had the same thing happen yesterday. Except I noticed that with the knob all the way over on cold, the air was still a little warm. When I went to turn the knob through it's range to make sure it was working, it wouldn't go the whole way....when I pushed, I heard and felt the same snap.

What's the fix for this? I'm sure I can figure it out, but would rather save the time of discovery if someone else has already resolved it at some point. Thanks!

 

[brian2sun]

I'm not looking at mine right now, but I had that issue a few years ago and mine had a cable or lever or something that went through the firewall to a valve inside the engine compartment. I had to lube that valve and lever and it got smooth. I'm not sure if my '97 is different than yours though, hope it helps.

 

[Nelsonmd]

yeah, I have the exact same problem, except it isn't temp dependent at all, it is always really sticky.

I would love to hear someone's solution to this.

 

[SkidPalace]

Nice job on the bump, I actually thought I bumped it myself a few weeks ago. It must have been on YotaTech.
I think I have a thread with pics either here or over on YT.
Fourth year in a row that the first use of heat of the year renders the temp selector almost frozen. If you force it, it will jump or strip (or whatever is going on). Once you get it moving, it will free up, but it is always tight.
Brian2Sun, thanks for that, I hadn't thought of an other linkages that went in to the engine compartment. I will check that out.

 

[Nelsonmd]

I might have a different problem since mine is always stiff, though as it gets colder now I will see if it gets worse. I also don't think that I have stripped the knob, though I base that on absolutely nothing...

 

[004Gunner]

Massive 3 year bump.....because I had the same thing happen yesterday.

No dude, that's a 4 year bump! This :trophy: is yours for one of the "best thread resurrections" ever! This :trophy: is also yours for "outstanding search performance"!

This :whipping2 is for me because I contributed absolutely nothing to resolving your problem

 

[quicksilvr]

No dude, that's a 4 year bump! This :trophy: is yours for one of the "best thread resurrections" ever! This :trophy: is also yours for "outstanding search performance"!

This :whipping2 is for me because I contributed absolutely nothing to resolving your problem

ROFL....:lmao:


Here's my update: After hearing that snap yesterday, the knob would not turn all the way to the cold stopping point. So I forced it back, and sure enough it snapped again. Now it goes through it's full range properly, and it's actually pretty easy to turn. However! When it's on full cold (and the outside temp is in the 40's) my vent air still feels warm. At highway speed. So, something is slightly messed up, because it's getting heated more than it should. Plus when I turn the A/C on, it just feels a little cool. Not ice cold like it should when you run the A/C in the fall on full cold. lol.

 

[quicksilvr]

Ok, I fixed it, and it was pretty easy. There is a cable that runs in plain sight under the dash of the passenger footwell. That thing controls the "blend door", and is adjusted when you turn the temperature control knob.

My entire cable had gotten knocked loose from a little metal bracket that clamps down on the sheath and holds it in place.....so instead of just the inner cable sliding in the sheath and moving the blend door....the whole cable was moving when I turned the knob, so nothing was pushing on the blend door to move it.


For people that are experiencing stiff knob turning: either the cable is not sliding in the sheath smoothly, or the blend door is all gunked up. Getting the blend door contraption out might be a pain...I dunno...I didn't have to mess with it. But that's what makes it hard to turn the knob.

 

[Satter]

Would it be possible to get a pic of this? I'm sure this is something that happens to every car with this time of temp control eventually. It would be good to know what to look for for future reference.

 

[quicksilvr]

Would it be possible to get a pic of this? I'm sure this is something that happens to every car with this time of temp control eventually. It would be good to know what to look for for future reference.

Yeah, I can snap a pic. Even when you're driving, if you look over at the passenger footwell, you'll see a black cable going right underneath a black box under the dash. That's the cable. It's held by a clip that is close to the center console.

 

[SkidPalace]

If you re-read my original post from four years ago, I had described the same exact scenario. I definitely had a picture attached, too. It must have disappeared over the years.
When I disconnect the cable from the blend door lever, the knob will turn smooth as silk. It seems to be the blend door itself that is gunking up and binding. I was hoping someone else had found this before and knew where to lube the blend door mechanisms. I know it is not and easy task to get access to it.
The fact that it is almost frozen upon first use of the season, and then loosens up to some degree of usability tells me that it is probably a gunky old lube situation. I'm going back in...

This pic is taken from the passenger floor, looking up under from behind the center dash. The black cable is shown removed from the barbed post in the right of the pic.

 

[SkidPalace]

So I went back in there and had another look and I still can not figure how to free up the mechanism. There are several contraptions linked together to operate the hvac system. There are two or three other cables attached to that big white plastic linkage. There is definitely a cable that runs through the firewall and into the engine compartment, as Brian2sun mentioned. That actuates the water valve to let hot water into the heater core. In my case, the valve was free as a bird, so it is not adding resistance in my situation. My guess is the cable link to the cooling unit is the one giving the works the most resistance. I will have to spend more time isolating and testing the control cable there.
I lubed the hell out of all the connections, posts and pivots I could find with Fluid Film and hopefully it will free up in time.
The clicking of the knob when being forced is definitely NOT the cable slipping in the clamp. The knob is certainly jumping a gear tooth or two inside the knob assembly itself. Until I can track down what is gumming up the system, I can only assume the temp knob will fail in another year or two.

 

[SkidPalace]

Update

So it seems that my fluid film lube job has been progressively getting the job done. My temp knob is moving much more freely it seems by the week. More free than it has in years.
I recall spraying at least five or six pivots and slides in the works from both the left and right sides of the center dash console.

 

[tahoe22]

I'm pretty sure I have this exact problem in a 2k4R. When I turn the temp knob to where the heat kicks in, I hear a "clicking" sound under the passenger side of the dash. Is the fix to simple put the eyelet on the right side of the photo onto the white post that is directly below it?

Thanks!

 

[4R99JB]

I'm pretty sure I have this exact problem in a 2k4R. When I turn the temp knob to where the heat kicks in, I hear a "clicking" sound under the passenger side of the dash. Is the fix to simple put the eyelet on the right side of the photo onto the white post that is directly below it?

Thanks!

Excellent timing for resurrecting this post. Just experienced a cool spell here in East Texas. I haven't actually used any heat yet. But I'll be informed. Thanks.

GREATEST FORUM ON THE NET! :keyboard:

 

[4R99JB]

OOPS! I should probably actually answer your question. Yes, it appears so. If you have an assistant I'd start by working the dash control and holding the part that attaches to the blend control; prior to reattaching it. This way you'll be able to determine if there is any other binding / issues whthout causing any collateral damage. Curious why it's detached to start with?

Good luck. :driving:

 

[tahoe22]

Well, it was attached-but I've managed to "fix" that in the process of trying to get the white piece to move. I can't get that cable or the white plastic piece to budge for the life of me.

 

[4R99JB]

Rather than just talking $h!t I thought I'd post a couple of pictures. Cold and hot on dial control. Sorry I don't know how to post, write, post, write...

 

[4R99JB]

I must learn how to edit photos & text...Sorry, but you can see that the blend valve also controls the heater valve on the engine side of the fire wall. See if you can get that valve to move. From the, better, photo on page one you can clearly see that the metal ring should also be attached to the post to control the engine coolant to produce heat.

Good luck. :smashputer: